Expanded phenotypic spectrum of FOXL2 Variant c.672_701dup revealed by whole-exome sequencing in a rare blepharophimosis, ptosis, and epicanthus inversus syndrome family.

INTRODUCTION: Blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES) is a rare genetic disease with diverse ocular malformations. This study aimed to investigate the disease-causing gene in members of a BPES pedigree presenting with the rare features of anisometropia, unilateral pathologic myopia (PM), and congenital cataracts. METHODS: The related BPES patients underwent a comprehensive ocular examination. Next, whole-exome sequencing (WES) was performed to screen for the disease-causing genetic variants. A step-wise variant filtering was performed to select candidate variants combined with the annotation of the variant's pathogenicity, which was assessed using several bioinformatic approaches. Co-segregation analysis and Sanger sequencing were then conducted to validate the candidate variant. RESULTS: The variant c.672_701dup in FOXL2 was identified to be the disease-causing variant in this rare BPES family. Combined with clinical manifestations, the two affected individuals were diagnosed with type II BPES. CONCLUSION: This study uncovered the variant c.672_701dup in FOXL2 as a disease causal variant in a rare-presenting BPES family with anisometropia, unilateral pathogenic myopia, and/or congenital cataracts, thus expanding the phenotypic spectrum of FOXL2.

Genetic Screening Revealed Latent Keratoconus in Asymptomatic Individuals.

PURPOSE: To adopt molecular screening in asymptomatic individuals at high risk of developing keratoconus as a combinative approach to prevent subclinical patients from post-refractive surgery progressive corneal ectasia. METHODS: In this study, 79 Chinese and nine Greek families with keratoconus were recruited, including 91 patients with clinically diagnosed keratoconus as well as their asymptomatic but assumptive high-risk first-degree relatives based on underlying genetic factor. Mutational screening of VSX1, TGFBI, and ZEB1 genes and full clinical assessment including Pentacam Scheimpflug tomography were carried out in these individuals. RESULTS: Five variants in VSX1 and TGFBI genes were identified in three Chinese families and one Greek family, and four of them were novel ones. Surprisingly, ultra-early corneal changes in Belin/Ambrosio Enhanced Ectasia Display of Pentacam corneal topography together with co-segregated variants were revealed in the relatives who had no self-reported symptoms. CONCLUSIONS: Variants of VSX1 and TGFBI genes identified in both the clinically diagnosed and subclinical patients may cause the keratoconus through an autosomal dominant inheritance pattern, with different variable expressivity. Combining genetic with Belin/AmbrosioEnhanced Ectasia Display can be used to identify patients with latent keratoconus. This study indicates that genetic testing may play an important supplementary role in re-classifying the disease manifestation and evaluating the preoperative examination of refractive surgery.

Unraveling the genetic causes in large pedigrees with gout by whole­exome sequencing.

Gout is a common type of inflammatory arthritis that is clinically and genetically heterogeneous. The genetic aetiology remains unclear, and mainly relies on previous genome­wide association studies focused on sporadic cases. The present study aimed to identify the genetic basis of gout in three families using whole­exome sequencing (WES). WES was performed in the probands, and family members were involved in the co­segregation analysis. In total, three deleterious rare or novel missense mutations were identified in ATP­binding cassette super­family G member 2 (ABCG2), protein kinase CGMP­dependent 2 (PRKG2) and adrenoceptor ß3 (ADRB3) genes in three different families. In addition, certain gout­associated candidate genes were revealed to be shared among the co­expression and protein­protein interaction (PPI) networks of ABCG2, PRKG2 and ADRB3. Furthermore, the disease ontology analysis of the genes present in the co­expression network exhibited significant (P<0.05) enrichment in hyperuricemia, gout, cardiovascular system disease and metabolic disease. In addition, genes involved in the PPI network were significantly enriched in the purine nucleoside monophosphate biosynthetic process, urate transport and biological processes associated with glycose metabolism. Collectively, to the best of our knowledge, the present study was the first to use WES to identify three candidate rare or novel deleterious mutations in three families with gout. The present results provided novel insights that may improve the current understanding of the molecular genetic basis underlying gout. Importantly, the present results may facilitate the improvement of clinical diagnosis and the development of novel personalized therapies.

Mutation spectrum and genotype-phenotype correlation of inherited retinal dystrophy in Taiwan.

BACKGROUND: Inherited retinal dystrophy (IRD) is a group of irreversible retinal degenerative disorders with significant genotypic and phenotypic heterogeneity, which cause difficulty in making a precise clinical diagnosis. Furthermore, the mutation spectrum of IRD in Taiwan remains unknown. Therefore, our study focused on investigating the spectrum of mutations among Taiwanese families with IRD using targeted exome sequencing (TES) technology. METHODS: We recruited a total of 60 unrelated Taiwanese families with IRD; most of them were retinitis pigmentosa. We employed TES to investigate 284 candidate genes. Bioinformatics analysis, Sanger sequencing-based co-segregation testing, and computational assessment were performed to validate each mutation and its pathogenicity. The genotype-phenotype correlation was analysed in all patients with mutations defined in the guidelines provided by the American College of Medical Genetics. RESULTS: We successfully identified genetic causes in 32 families (detection rate of 53.3%). Among them, 16 had a sporadic inheritance (16/36, 44.4%); eight had an autosomal recessive inheritance (8/14, 57.1%); four had an autosomal dominant inheritance (4/5, 80%); four had an X-linked inheritance (4/5, 80%). Among 38 pathological mutations in 19 known genes, 20 mutations are reported here for the first time. Novel mutation spectrum and genotype-phenotype correlations were revealed as well. CONCLUSION: Here we achieved a detection rate of 53.3% and elucidated the mutation spectrum in Taiwanese families with IRD for the first time. The results indicated that CYP4V2 and USH2A might be the most common pathogenic genes in IRD patients in Taiwan.

Functional characterization of CEP250 variant identified in nonsyndromic retinitis pigmentosa.

Retinitis pigmentosa (RP) is the most common manifestation of inherited retinal diseases with high degree of genetic, allelic, and phenotypic heterogeneity. CEP250 encodes the C-Nap1 protein and has been associated with various retinal phenotypes. Here, we report the identification of a mutation (c.562C>T, p.R188*) in the CEP250 in a consanguineous family with nonsyndromic RP. To gain insights into the molecular pathomechanism underlying CEP250 defects and the functional relevance of CEP250 variants in humans, we conducted a functional characterization of CEP250 variant using a novel Cep250 knockin mouse line. Remarkably, the disruption of Cep250 resulted in severe impairment of retinal function and significant retinal morphological alterations. The homozygous knockin mice showed significantly reduced retinal thickness and ERG responses. This study not only broadens the spectrum of phenotypes associated with CEP250 mutations, but also, for the first time, elucidates the function of CEP250 in photoreceptors using a newly established animal model.

Retinal miRNAs variations in a large cohort of inherited retinal disease.

BACKGROUND: Although great efforts have been paid on identification of genetic predisposition in the inherited retinal disease (IRD), genetic causes of a large proportion of patients remain a mystery. This dilemma makes us attempt to speculate that genetic components other than coding genes might be an additional pool predisposing IRD. In this study, we aim to perform a mutational screening in a large cohort of IRD patients with a particular focus on retina-specific or abundant microRNAs (miRs). MATERIAL AND METHODS: A total of 324 unrelated patients with IRD were recruited. Targeted next-generation sequencing (tNGS) was performed to survey genetic mutations in 32 known miRs highly expressed in the retina, followed by validation with Sanger sequencing, co-segregation analysis in each family, and computational assessments. RESULTS: Novel genotype-phenotype associations have been uncovered. In total, six different variants in the miRs were identified, including four rare ones, miR-216a (n.56C>A), miR-216b (n.43_44insG), miR-7-2 (n.107C>T), and miR-7-3 (n.95G>A). The other two variants, miR-182 (n.106G>A) and miR-216a (n.105T>A), were considered as polymorphic. CONCLUSIONS: We for the first time screened candidate retinal miRs in patients with IRD. Although there is no convincing evidence that these variants are responsible for the IRD, the results enhance the current knowledge of the associations between IRD and miRNAs variants.

Unraveling the genetic cause of a consanguineous family with unilateral coloboma and retinoschisis: expanding the phenotypic variability of RAX mutations.

Ocular coloboma is a common eye malformation arising from incomplete closure of the human optic fissure during development. Multiple genetic mutations contribute to the disease process, showing extensive genetic heterogeneity and complexity of coloboma spectrum diseases. In this study, we aimed to unravel the genetic cause of a consanguineous family with unilateral coloboma and retinoschisis. The subjects were recruited and underwent specialized ophthalmologic clinical examination. A combination of whole exome sequencing (WES), homozygosity mapping, and comprehensive variant analyses was performed to uncover the causative mutation. Only one homozygous mutation (c.113 T > C, p.I38T) in RAX gene survived our strict variant filtering process, consistent with an autosomal recessive inheritance pattern. This mutation segregated perfectly in the family and is located in a highly conserved functional domain. Crystal structure modeling indicated that I38T affected the protein structure. We describe a patient from a consanguineous Chinese family with unusual coloboma, proven to harbor a novel RAX mutation (c.113 T > C, p.I38T, homozygous), expanding the phenotypic variability of ocular coloboma and RAX mutations.